I watched it happen once in my front yard when I was a kid. She did it while they were still mating. She took his head off at the base of the long neck, ate it, and walked away with the rest of him still mounted on her back. I wish I’d had a camera phone, but it was the ’70s.

Not true. When I was about 12 I watched a pair of mantises mating on the edge of our driveway. She chewed his head off at the base of the neck, and then ate the head from the neck up. She then walked away into the grass with his body still mounted on/in her. They weren’t captive or stressed in any way.